The output drive strength can be configured in CyberClocks software in the Advanced Mode window that will change the Output Impedance.
The output impedance for each setting is as follows:
Low - 26.8 ohms.
M Low - 18 ohms.
M High - 16 ohms.
High - 12.8 ohms.
The output drive strength default setting for Cyberclocks is "M Low", which corresponds to 18 ohms output impedance.